Assessment versions

Published (reviewed and quality assured)

Justification for indicator selection

Snow covers more than 33 % of the land surface north of the equator from November to April. It reaches a maximum of about 45.2 million km2 in January, and a minimum of about 1.9 million km2 in August (Clark et al., 1999). Snow cover is an important feedback mechanism of the climate system. The extent of snow cover depends on the climate, for example on temperature and precipitation, and on solar radiation. But it also influences the climate and climate-related systems because of its high reflectivity, insulating properties, effects on water resources and ecosystems, and cooling of the atmosphere. Thus a decrease in snow cover reduces the reflection of solar radiation, contributing to accelerated climate change. Changes in the extent, duration, thickness and properties of snow cover can affect water availability for domestic use, navigation and power generation. Changes in snow cover affect human well-being through influences on agriculture, infrastructure, the livelihoods of indigenous Arctic people, environmental hazards and winter recreation. Snow-cover retreat can reduce problems of winter road and rail maintenance, affecting the exploitation and transport of oil and gas in cold regions (UNEP, 2007; ACIA, 2004).Shallow snow cover at low elevations in temperate regions is the most sensitive to temperature fluctuations and hence most likely to decline with increasing temperature (IPCC, 2007a, b). For several of these impacts, adaptation can reduce the negative effects of snow-cover change. Some adaptation options, such as artificial snowmaking in the Alps to maintain tourism as a main source of income, have to be balanced against their negative implications for mitigation, due to increased energy use and greenhouse gas emissions.

Scientific references:

No rationale references
available

Indicator definition

Northern hemisphere snow-cover extent variation 1966-2005

Observed change in spring snow-cover duration 1970-2004

Annual number of days with snow cover over European land areas 1961-1990 and projected change for 2071-2100

Units

Policy context and targets

Context description

In April 2009 the European Commission presented a White Paper on the framework for adaptation policies and measures to reduce the European Union's vulnerability to the impacts of climate change. The aim is to increase the resilience to climate change of health, property and the productive functions of land, inter alia by improving the management of water resources and ecosystems. More knowledge is needed on climate impact and vulnerability but a considerable amount of information and research already exists which can be shared better through a proposed Clearing House Mechanism. The White Paper stresses the need to mainstream adaptation into existing and new EU policies. A number of Member States have already taken action and several have prepared national adaptation plans. The EU is also developing actions to enhance and finance adaptation in developing countries as part of a new post-2012 global climate agreement expected in Copenhagen (Dec. 2009). For more information see: http://ec.europa.eu/environment/climat/adaptation/index_en.htm